Stacked projectors are generally project images that are intended to be aligned. For example, each stacked projector can project the same image, aligned onto a surface to increase the brightness of the image on the surface. In other situations, one or more of the stacked projectors can project a different image from the other stacked projectors, for example as an image surrounded by (e.g. inserted into) the aligned images projected by the other stacked projectors. However, even small differences in alignment of images projected by the stacked projectors can be noticeable to a viewer. While such alignment can be performed manually, the alignment can drift over time due to changes in the environment, and the like, requiring periodic manual maintenance. While some automatic techniques can be used to perform the alignment, such automatic techniques can be complicated to implement, requiring large processing and/or setup overhead.